this is aside from the question of shooting smokeless powder and modern shells in those guns, something that should never be done, though I have been lectured by folks who do so, including some who claim that they do so all the time, and that Damascus barrels are much stronger than modern steel.
I grew up doing it because I didn't known any better. Dad always had a few hammer guns around and I shot modern 2 3/4 shells out of them. I won't do that now but maybe thats where my lack of fear for them comes from. There have been tests done that proved they were just as strong.